Alkenes to Methoxyalkenes or Hydroxyalkenes

Addition of phenyl tellurium tribromide to terminal olefins in methanol as the reaction medium, yields 2-methoxyalkyl phenyl tellurium dibromide. Hydrolysis of the dibromides with sodium hydroxide in aqueous THF produces 2-methoxyalkyl phenyl tellurium oxides, which, upon heating at 240°, form 2-methoxyalkenes .  

A similar reaction carried out with cyclohexene led to the formation of 3-methoxycyclohexene When this reaction sequence is carried out with internal olefins, the methoxyalkyl phenyl tellurium oxides are not stable and decompose to methoxyalkenes in the basic medium required for the hydrolysis of the methoxyalkyl phenyl tellurium dibromides(see p. 583). Aqueous solutions of sodium hydrogen carbonate cause the same transformations at a slower rate . Thus, 5-hydroxy and 5-methoxy-4-hexyl phenyl tellurium dibromide were converted to the corresponding 5-substituted 3-hexenes. 3-Hydroxy- and 3-methoxy-l-cycloheptene were similarly obtained.  

1-Decene and phenyl tellurium tribromide reacted in methanol to produce 2-methoxydecyl phenyl tellurium dibromide, which was hydrolyzed to the tellurium oxide. Treatment of the tellurium oxide with 3-chloroperoxybenzoic acid in methanol give 1,2-dimethoxydecane in 84% yield . 

When 2-phenyl-2-methoxy-2-R-ethyl or -propyl phenyl telluroxides (obtained from phenylethylenes and phenyl tellurium tribromide in methanol followed by hydrolysis of the tellurium dibromide) were treated with 3-chloroperoxybenzoic acid in methanol at 20°, the phenyl group migrated to the methylene group from which the tellurium moiety had been 

Cyclopent-l-en-3-one and cyclohex-1-en-3-one react with diisobutylalumino phenyl tellurium. The 1,4-addition products condense with aldehydes to give 2-hydroxyalkyl-3-oxocycloalkyl phenyl telluriums that are converted upon treatment with 3-chloroperoxy-benzoic acid to 2-hydroxyalkylcycloalk-l-en-3-ones.  

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